Steel retainer



July 17, 1928.

WQPRELLWITZ STEEL RETAINER Filed March '12, 1928 mum IN V EN T 0R. 11 211; 1121 1 491 11012} BY aa ATTORNEY.

Patented July 17, 1928.

UNITED} STATES.

} 1,677,530 PATENT; F FICE.

WILLIAM ZERELLWITZ, 0E EAs'roN, rENnsrLvArirA, ASSIGNOR' 'ro rrmru sonL-n'am) COMPANY, OF JERSEY CITY, NEW JERSEY, A coaromrron or nEwJ BsEY.

STEEL EETAI NER;

Application filed March 12, 1928. Serial No. 260,925.

.This invention relates to'rock drills, but more particularly to a steel retainer adapted to. be attached to fluid actuated rock drills of the hammer type in whichthe piston reciprocates relatively to the drill steel.

The objects of the invention are to main tain the drill steel in the front head, to

insure against unauthorized oscillation of. the retainer from the retaining position and to strengthen the retainer at those points at which itis subjected most severely to strains upon the impact of the drill steel against the retainer.. i

Other objects will be inpart-obvious and in part pointed out hereinafter.

In the drawings accompanying the specification andin which is illustrated one form which the invention may assume in'practice,

Figure 1 is an elevation of the front end of a rock drillhaving the invention applied thereto, T

Figure 2 is an elevation'of the front end of a rock drill showing'another view of'the retainer, and

Figure 8' is a transverse view taken through Figure 1 on the line 33 looking in the direction indicated by the arrows.

Referring to the drawings, the invention is shown applied to a rock drill only the front head A and a portion of thefcylinder B of which is shown. These parts, together with others not shown, comprise the casing of the drill .and are held in operative position by side bolts G disposed on opposite sides of the drill.

The front head A, among other functions serves as a guide for a working implement or drill steel D which may project through the front head A to a point near the cylinder B to receive the blows of a hammer piston (not shown) reciprocable in the cylinder. A collar E is formed on the drill steel D to abut the front end of the front head for limiting the distance which the drill steel may extend into the front head A.

On opposite sides of the front head are formed trunnions F of cylindrical shape. The trunnions F are in this instance off-set with respect to the longitudinal axis of the drill and may be located in any convenient position with respect to the extremities of the front head.

In accordance with the present invention, means are provided for preventing ejection of the drill steel D from the front head against the drill steel, and more particularly atthe time when there is insuflicient resist; ance to the cutting bit ofthe drill steel to I maintain said drill steel in its 'rearward-' most limiting position in the drill. These means comprise a steel retainer H which consists of a single piece of wire of square cross sectional form bent ,intermediatefits ends to form a yoke J. ,The yoke J is of U.-

shape and partly encircles the drill steel D forwardly of the collar E at a distance sufiiciently removed therefrom to permit limited endwise movement of the drill-steel D.

The yoke J has integral side arms K which extend in a rearwardly'direction on opposite sides of the front head- A and terminate at their rearwardends in spiral springs L which act as cushioning means for absorbing the jblows of the drill steel D upon the impact of the hammer piston,

againstthe yoke J. The-springs L may con sist of any-suitable number of coils dependmg on the type ofqfronthead: whereon the retaineris usediandthe position in which it is. desired to mountjtheretainer. The in ner coils O of the: springsL are ofsuch form side arms are brought to the inner sides of formed in opposite sides of the front head said side arms to lie slidably in grooves A and preferably near the front end thereof.

By twisting a portion of the side arms in the manner described, the cross sectional area is increased at this point. This is desirable since it is at this point that the retainer contacts with the front head and is therefore subjected'to severe angular stresses whenever the working implement strikes against the yoke J. Another desirable advantage of a retainer of this type constructed of square wire over retainers formed of wires'of other cross sectional forms, such as round Wire, is that aflat surface of the yoke is provided asa seat or abutment for the collar E of the as tosnugly receive-the trunnions F where 1 sence of resistance to the bit of the drill steel,

will serve to prevent ejection of the drill steel from the front head, the blows of the drill steel against the yoke being absorbed by the coil spring L. Whenever it is desired to change drill steels, the retainer I-I may be rocked to the releasing position Where it will be held by the gripping action of the inner coils O on the trunnions F. After anotherdrill steel has been inserted in the front head, the retainer Il may again be rocked to the retaining position.

I claim: I

1. In a steel retainer for rock drills, the combination of a front head having grooves in opposite sides, a drill steel extending into the front head, trunnions on the front head, a retainer comprising a piece of rectangular wire bent to form a yoke adapted to act as an abutment for the drill steel, side arms on the yoke having integral spiral springs, the innermost coils of said springs being adapted to pivotally receive the trunnions, and locking portions on the side arms twisted about the longitudinalaxis of the side arms to enable a corner of said locking portions to lie in the grooves'for locking the retainer in the retaining position.

2. In a steel retainer for rock drills, the combmation of a front head having grooves in opposite sldes, a drill steel extending 1nto the front head, trunnions on the fronthead,

a retainer comprising a piece of square wire bent to form a yoke adaptedto'act as an abutment for the drill steel, side arms on the yoke having integral spiral springs, the innermost coils of said springs being adapted to pivotally receive the trunnions, and

grooves for locking the-retainer 1n the ref taining position. v

3. In asteel retainer for rock drills,the combination of a front head having grooves in opposite sides, a drill steel extending into the front head, trunnions on the front head, a retainer comprising a piece of square wire bent to form a yoke adapted to act as;an abutment for the drill steel, side arms on the yoke having integral spiral. springs, the innermost coils of said spring being adapted to pivotally receive the trunnions, and lock ing portions on the side arms formed by twisting portions of said side arms substantially one-eighth turn about the longitudinal axes of the side arms to enable corresponding corners of said locking portions to lie in the groovesfor locking the retainer in the retaining position.

In testimony whereof I have signed this specification.

] WILLIAM PRELLWITZ, 

